Lay down pipe stinger tuning - jets, fcv, etc.

Jcary85 · Mar 9, 2020

Hey all - I’m running a PFP on an ET1107. I’ve read as much as I could find on pipe tuning but it seems like people really only mess with the FCV going to the stinger and don’t touch the jet. I went from a 90 to the original 120 this weekend and also tightened the FCV a good bit and the thing really woke up. As I understand it, less water at the stinger should result in more bottom as it’s essentially making the stinger seem large. My theory on what happened this weekend is that I cut off water to the stinger under a certain RPM which increased my bottom but increased the jet which cones on at some higher RPM now and that helped the top end (smaller stinger opening because more water)

Is my theory correct? Should I be tuning by water box temp? That’s how certain experts have told me to tune the water box in the past (get it to 150F), but that seems like the wrong approach. It seems like tuning to an RPM where the water comes on should be the starting point followed by tuning the jet to get the most mid-top end power. Maybe I’m way off idk.

Harbor · Mar 9, 2020

I left in the 120 jet, actually might be 125.... and discovered the same thing as you... cranking down the Fcv made more bottom end.... I was expecting the opposite.....

water box Got into the 130’s..in 55 deg water.. I stopped there

CARBONX2 · Mar 9, 2020

Less water to stinger = less back-pressure in pipe = more bottom end. There is a limit but more likely to be found on a smaller engine

Chase Musetti · Mar 9, 2020

I’m curious to hear about these COMP stingers and the details and rationale behind how they work? How much can you possibly change at the stinger besides diameter and amount of water injected?

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Wetbuffalo · Mar 9, 2020

Chase Musetti said:
I’m curious to hear about these COMP stingers and the details and rationale behind how they work? How much can you possibly change at the stinger besides diameter and amount of water injected?

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The COMP stinger is TNT pipe thing. Not. PFP

Chase Musetti · Mar 9, 2020

Wetbuffalo said:
The COMP stinger is TNT pipe thing. Not. PFP

Gotcha- well either way the thread is about lay down pipes so I’m still very curious.

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Wetbuffalo · Mar 9, 2020

Chase Musetti said:
Gotcha- well either way the thread is about lay down pipes so I’m still very curious.

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With the TNT comp stinger the pipe is trapping more exhaust gases, by extending the stinger into the body of the pipe more. Back to back testing on my 964 showed a good increase in bottom and mid range performance.

Chase Musetti · Mar 9, 2020

Wetbuffalo said:
With the TNT comp stinger the pipe is trapping more exhaust gases, by extending the stinger into the body of the pipe more. Back to back testing on my 964 showed a good increase in bottom and mid range performance.

That’s interesting- thanks for the info- didn’t even know it was a thing/option till recently.

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stefan · Mar 10, 2020

What impeller you Got on your 1107 ?

Jcary85 · Mar 10, 2020

stefan said:
What impeller you Got on your 1107 ?

9/16 -3 cutback on a skat setback mag 155. I’m playing with pump tuning right now. Switching trim systems and will have bigger nozzles so I’ll prob end up at 11/17 but the 9/16 seems just about perfect.

stefan · Mar 11, 2020

Jcary85 said:
9/16 -3 cutback on a skat setback mag 155. I’m playing with pump tuning right now. Switching trim systems and will have bigger nozzles so I’ll prob end up at 11/17 but the 9/16 seems just about perfect.

Okai i am running a 12/18 with dry pipe, i am going too try wet pipe again i realy liked the bottom end hit

Jcary85 · Apr 9, 2020

Small update here - water temps are now getting into the 60s and my water box is getting too hot. Haven’t checked the temp but water will steam off if it. I hesitate to fix this by opening the FCV as i know it will reduce my bottom end power. Any thoughts on what’s best to do? Should I just live with the hot water box? Anyone ever run a spray bar somewhere into the water box to keep it cool without impacting the stinger water flow?

Chase Musetti · Apr 9, 2020

Temp it just to see how hot it’s actually getting. The JM lay down style waterbox has a bung welded to it for that option, so it can be done to whatever box you got now.

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